1. Field of the Invention
The present invention relates to remote controlled, unmanned inspection vehicles. More specifically, the present invention relates to inspection vehicles capable of entry into highly constrained spaces, and traversing nonhorizontal and/or nonflat ferromagnetic surfaces through magnetic adhesion to such surfaces.
2. Description of the Related Art
It is frequently necessary to perform inspections of machinery, storage tanks, etc. where highly constrained entry points and/or environmental hazards make direct human inspection either impossible or inadvisable. Examples include electrical generators and other machinery having highly constrained travel spaces between the various moving components, storage tanks wherein chemical hazards are present, such as underground gasoline tanks, and pools containing nuclear reactor spent fuel wherein radiation hazards are present. Frequently, access to various regions that must be inspected requires traversing nonhorizontal surfaces, such as angled components and/or walls, and/or nonflat surfaces, such as the exterior or interior of pipes.
One proposed remote controlled inspection vehicle is described in U.S. Pat. No. 5,363,935, issued to H. Schempf et al. on Nov. 15, 1994. The vehicle includes at least one frame member supporting a continuous track, a magnet, a fixed magnetic element, and a movable magnetic element. The movable magnetic element forms one side of a rotatable cylinder surrounding the drive shaft operatively connecting the motor and tracks, so that it may engage the drive shaft when movement is desired. The fixed magnetic element includes a pair of magnetic pieces on either side of the cylinder, with one piece including the permanent magnet, and legs terminating in rollers contacting the tracks. Each track cleat includes a nonmagnetic center portion and magnetic end portions. When the movable magnetic element is in a first position wherein it forms a magnetic flux path between the fixed magnetic pieces, thereby forming a complete flux path including the movable piece, 2 fixed pieces, ends of the track cleats, and the surface upon which the vehicle is travelling, the vehicle is magnetically secured to the inside surface of the tank. When the movable magnetic element is rotated to its second position, the magnetic flux path is broken, and the vehicle is not magnetically secured to the interior surface of the tank. A pair of such frame units are connected to either end of a sensor unit through steering units. An alternative embodiment utilizes a track wherein the cleats are made from magnetic material with copper bars extending across the width of each end of the cleats, and a ferromagnetic plate extending across the length of the plate. The ferromagnetic plate is surrounded by a coil in electrical contact with the copper bars at each end. Electrical current is supplied to additional copper bars adjacent to the track, so that when the copper bars extending across the width of the track are brought into contact with these copper bars, the cleat becomes an electromagnet. The steering unit includes a yaw actuator and a pitch actuator, both of which are actuated by electric motors and gear arrangements. Sensors may include ultrasonic inspection sensors, cameras, acoustic navigation systems, vapor sensors, radiation detectors, etc. A tether line is used to supply power and control functions. This patent does not describe a means for rotating the tracks of the vehicle around their longitudinal axis.
U.S. Pat. No. 4,828,059, issued to S. Naito et al. on May 9, 1989, describes a wall-crawling machine having permanent magnets within the tracks. One embodiment uses two sets of tracks, pivotally connected with each other, so that movement of the rear track towards a wall causes the forward track to align itself with the wall and adhere to the wall. Movement of the front track up the wall then angles the rear track to align it with the wall. A second embodiment utilizes permanent magnets attached to a pivoting arm to pull the vehicle up onto a wall. A third embodiment has laterally-extendable tracks for performing a transverse walking function.
U.S. Pat. No. 4,664,212, issued to K. Nagatsuka et al. on May 12, 1987, describes a remote controlled, tracked vehicle having suction chambers with apertures in the tracks. A centrally mounted suction apparatus is mounted adjacent to the central portion of each track, and sucks air through the suction chambers located near the central portion of the vehicle to retain the vehicle on a surface.
U.S. Pat. No. 5,894,901, issued to N. Awamura et al. on Apr. 20, 1999, describes an endless magnetic track for a vehicle, having a plurality of magnets coupled in series with the chain, and a means for providing slack within the tracks when traversing uneven terrain.
Accordingly, a remote controlled inspection vehicle capable of fitting into extremely small spaces, for example, between the rotor and stator of an electrical generator, is desired. Additionally, a remote controlled inspection vehicle having propulsion units that are rotatable about their longitudinal axis for traversing concave and convex surfaces, for example, the interior and exterior of pipes, is desired. Further, a remote controlled inspection vehicle having an adjustable distance between the propulsion tracks is desired. A remote controlled inspection vehicle having replaceable modular tracks for different operations is also desired.
The present invention is a remote controlled inspection vehicle for performing inspections in areas inaccessible to human inspectors due to small size and/or hazardous conditions.
The inspection vehicle of the present invention includes at least one frame, dimensioned and configured to receive a pair of drive modules. The frame includes a longitudinal beam that is preferably hollow, permitting it to contain wiring for supplying electrical power and control signals, and for transmitting information detected during the inspection. Front and rear transverse beams are located at each end of the longitudinal beam, and are dimensioned and configured to support the drive modules, and to pivotally secure the frame to another frame and/or a tail.
Each drive module includes a motor, a gear box operatively connected to the motor, track drive wheels operatively connected to the gear box, and a continuous track. Each drive module is dimensioned and configured to be mounted on one side of the frame, supported between the front and rear transverse beams. A magnet, preferably a permanent magnet, is surrounded by the continuous track, and is dimensioned and configured to secure the vehicle to a ferromagnetic surface upon which the track is placed. The drive module may also include an encoder operatively connected to the motor, and being dimensioned and configured to transmit an electronic signal corresponding to a rotation of the motor. The drive module includes a mounting bracket at each end, with each mounting bracket having means to secure the mounting bracket to either the front or rear beam of the frame. One preferred means is a plurality of holes in both the frame and the mounting bracket, so that the distance between the drive module and the frame""s longitudinal member may be selected as desired by lining up the appropriate holes, and bolting the bracket to the frame. The brackets also include a pivot, dimensioned and configured to permit the drive module to pivot about its longitudinal axis, thereby permitting the track to lie substantially flat when the vehicle is traversing a nonflat surface, for example, the inside or outside of a pipe.
The front and rear edges of the frame include means for pivotally securing the frame to an identical frame, to an effector, and/or to a tail. One preferred means is a spring-biased hinge, defining a pivot substantially parallel to the front and rear transverse beams 22,24. The hinge is preferably spring-biased to maintain the components in a linear fashion. Typically, a complete vehicle will include either one or two such frames, with one frame being selected where minimized vehicle size is priority, and two frames being selected where the greater adhesion to the surface provided by the additional magnetic track modules is desirable. A tail may be hingedly secured to the rearmost frame to aid insertion into the location where inspection is desired. The vehicle may also include various effectors, which may preferably be hingedly secured to the vehicle""s front end, although other locations within the vehicle are permissible.
Several different effectors may be utilized with a vehicle of the present invention. For example, the effector may include a hammer mechanism designed to strike a surface, and a capacitive measurement probe to sense movement of the surface. The end effector may also include a camera. Another possible effector includes a loop cable and reference source for generating a magnetic field within the effector, a reference coil, and a sense coil on the underside of the effector. The difference in magnetic fields can indicate shorts between generator laminations. Other possible end effectors include ultrasonic inspection sensors, acoustic navigation systems, vapor sensors, and radiation detectors.
In use, the desired vehicle components may first be assembled. The modular construction of the vehicle permits the various components to be assembled in many different configurations, for example, any drive module may be placed anywhere on either the right or left side of the vehicle. A typical completed vehicle will include either one or two frames, depending on the size and/or ability to retain itself on a ferromagnetic surface. Drive modules with different size tracks may be utilized, depending upon the terrain and/or space limitations of the environment wherein inspection is desired. The tail may be mounted on the back end of the vehicle to assist in placing the vehicle in the desired location. The appropriate effector is mounted on the vehicle, depending upon the desired inspection to be performed. The vehicle is then inserted into the desired location, for example, between the rotor and stator of an electrical generator, wherein the vehicle may traverse either any horizontal surface, or any ferromagnetic surface to which the magnets inside the tracks may adhere. Power and control signals are supplied to the vehicle through cables extending from a remote controller to the vehicle, and data retrieved by the end effector are transmitted back to the remote controller for collection and analysis through additional cables. The encoders transmit signals back to the remote controllers corresponding to rotations of the motors, thereby permitting the position of the vehicle to be calculated based on the distance the vehicle will travel per rotation of the motor. Each drive module may be driven at different speeds when steering is desired, driving the tracks on one side of the vehicle at a faster speed than the tracks on the other side of the vehicle. If desired, it is possible to drive the tracks on one side of the vehicle one direction and the tracks on the other side of the vehicle the other direction, so that the vehicle may rotate about a stationary point. Additionally, an optional camera may assist in determining the location of the vehicle. The vehicle will traverse the various surfaces within the environment, perform the desired inspections, transmit the information back to the operators, and be retrieved from the environment.
It is therefore an aspect of the present invention to provide a remotely controlled inspection vehicle for operation within environments where space limitations and/or hazards prevent direct human inspections.
It is another aspect of the present invention to provide a remote controlled inspection vehicle capable of fitting into unusually small spaces.
It is a further aspect of the present invention to provide a remotely controlled inspection vehicle wherein the drive modules may pivot about the longitudinal axis, and the frames, effectors, and tail pivot with respect to each other about a transverse axis, thereby permitting maximized contact between each of the tracks and various irregular surfaces.
It is another aspect of the present invention to provide a remote controlled inspection vehicle having modular, interchangeable components.
It is a further aspect of the present invention to provide a remote controlled inspection vehicle wherein the distance between tracks within each frame may be varied as desired.
These and other aspects of the invention will become apparent through the following description and drawings.